Viton® News 1 - Article 5

Viton® in Ultra-Low Emission Fuel Tube From Nolato Sunnex

The ultimate "green" goal for the motor car is zero emissions of environmentally harmful substances. That's a tough challenge for men, machines and materials, but each year the industry must eliminate more and more of the weak links, particularly in fuel containment systems.

Conventional rubber hose connecting fuel tanks are a major source of such emissions. That is why Nolato Sunnex AB, of Sunne, Sweden, has developed its own concept in fuel pipes, claimed by the company's materials development manager, Johan Högberg, to be "considerably better sealed than conventional pipes, enabling them to fulfill tough US emissions requirements."

Viton® is the key

New Sunloph automotive fuel pipes from Nolato Sunnex are injection molded from two different materials. The stabilizing outer layer is a specialized blended rubber, and the critical inner layer - the key to its ultra-low permeability - is constructed of 100 percent DuPont Dow Viton® fluoroelastomer. "We chose Viton® because of its excellent resistance to a wide range of automotive fuels, and for its outstanding barrier properties," says Högberg.

In comparative tests, (see chart Fig. 1), hydrocarbon emissions from Sunloph pipes were as low as 28 mg HC/24h at 40°C compared with over 650 mg HC/24h for conventional NBR/PVC constructions.

"Among additional benefits, the new fuel pipes are precision molded for quick and simple assembly. And many different designs are possible with large variations available in the end-section diameter," he explains. Högberg describes Sunloph pipes with Viton® as a cost-effective alternative to extruded pipes with equivalent properties.

Success with TI Group

"New legislation created problems we were forced to solve," says Steiner Holth, department manager - Project/Development at TI Group Automotive Systems AS. The company supplies fuel systems to Volvo Car Corporation and Saab Automobile AB, among others.

"When American legal requirements on hydrocarbon emissions were disclosed, we set up a cooperative project between TI Group (Walbro Automotive) and Nolato Sunnex to develop systems in compliance with those emission demands," Holth adds.

"The technology for injection-molding dual-layer rubber pipes was extremely limited, so Nolato Sunnex produced its own tools to make the new concept possible. They were one of the first in the world to do so. In addition to very low hydrocarbon emissions, the primary benefits are moldability, high dimensional precision and cost-effectiveness.

Viton® is a registered trademark of DuPont Dow Elastomers

Note: This article, "Viton® in Ultra-Low Emission Fuel Tube From Nolato Sunnex," was provided by DuPont Dow Elastomers

Next Article: Viton® Shrugs Off Cold and Heat in Japanese Direct Injection Engines

Viton® is a registered trademark of DuPont Dow Elastomers.